Despite deteriorating health, Sykes could be seen on the West End stage late into his eighties and in 2005, starred in Harry Potter and the Goblet of Fire, before his death on 4 July 2012, aged 89.

The Heritage Foundation, which donated the plaque, said the Bayswater building was still listed as the registered address of Eric Sykes Limited and said three days before he died last summer Sykes told his agent Norma Farnes what he would like more than anything would be to visit Orme Court one last time.

The ceremony to mark the occasion on Sunday morning was also attended by actress June Whitfield, Dad's Army co-writer Jimmy Perry, Les Dennis and musician Les Reed .

Milligan, Sykes' friend and fellow comic and writer, who was best known for his work on the radio show The Goons in the 1950s, died in February 2002 at the age of 83.